1. Field of the Invention
The present invention relates to a liquid-crystal display device, and to a transparent film used as an optical compensatory film or the like in liquid-crystal display devices, etc.
2. Related Art
A liquid-crystal display device is used in various applications, as having the advantage that it is thin and lightweight. On the other hand, however, the liquid-crystal display device has a problem in that its viewing angle is narrow since the birefringence of the liquid-crystal cell therein varies depending on the viewing direction.
As one system improved in terms of viewing angle characteristics, a multi-domain system has been proposed, in which multiple domains differing in the alignment direction of the liquid-crystal molecules and in the rising direction of the liquid-crystal molecules during voltage application are formed in each pixel of the liquid-crystal cell. A liquid crystal cell with multi-domain structures can exhibit wide viewing angle characteristics since the difference depending on in which direction it is observed is reduced.
However, when it is observed in an oblique direction, not only the birefringence of a liquid-crystal cell may change but also the transmission axis of a pair of polarizers may shift from a perpendicular direction. As a result, when it is observed in an oblique direction, there may occur some problems of light leakage and color shift in the black state.
As a liquid-crystal display device capable of reducing the light leakage in the black state, JPA No. 2006-18285 has proposed a liquid-crystal display a liquid crystal panel comprising two substrates placed opposite to each other and a liquid crystal layer formed between the substrates, and equipped with a plurality of pixels, wherein each of the pixels is defined with at least two domains having different alignment characteristics; and the compensation film compensating for optical characteristics in a direction corresponding to a liquid crystal alignment direction of each of the domains.
The liquid-crystal display device described in JPA No. 2006-18285 comprises a compensatory film that compensates the optical characteristics in the direction corresponding to the liquid-crystal alignment direction of each domain of the liquid-crystal cell. For constructing the liquid-crystal display device of the type, for example, a compensatory film having a different retardation in the in-plane region in accordance with each domain of the liquid-crystal cell is fabricated, and the compensatory film is stuck to the liquid-crystal cell with micron-level positioning accuracy at every domain in the cell. However, such positioning technique is difficult, and is unsuitable to industrial scale mass-production.
Even in a liquid-crystal display device without multi-domain structures, plural domains with one pixel unit are formed in the liquid-crystal cell, and one pixel is divided into individual RGB domains of a color filter. Heretofore, for reducing the color shift in an oblique direction, it has been proposed to control the optical characteristics of a compensatory film in accordance with the respective wavelengths of RGB of a color filter. Like the above, however, the method is unfavorable in terms of the producibility, since the production process may require micron-level positioning accuracy or may require a micropatterning technique.